The book was recently selected as one of the 10 best books of October by Amazon’s editors, and Amazon editorial director Sara Nelson was especially impressed with how naturally Gilbert’s research on the locations to which Alma travels fit into the book. “It just really works as a novel,” Nelson said. "The research isn't overwhelming.”

NPR writer Lizzie Skurnick was won over, calling “Signature” “wonderful” and “one of the best of the year.” While many subjects are addressed in Gilbert’s narrative, says Skurnick, the book is “revelatory, not overwhelming.”

New York Times writer Janet Maslin called “Signature” “vibrant [and] hot-blooded,” though she noted that Gilbert’s attempts to capture a nineteenth-century tone in her writing can be a little obvious.

“It takes five affected little ‘ofs’ to make Alma — ‘ginger of hair, florid of skin….’,” she writes. “[But] “The Signature of All Things” remains engrossing…. Plausibility grows scarce during the book’s second half. But Ms. Gilbert’s wanderlust gets a chance to flourish. So does the love of knowledge that animates all of ‘The Signature of All Things.’”

USA Today critic Martha T. Moore was impressed with the fact that Gilbert “has clearly done a backbreaking amount of work” in order to accurately depict Alma and her time period.

“The characters around her are vivid and would make novels in themselves,” Moore wrote. However, she summed up Alma’s story as “a bit like the moss she studies: expansive but dense, admirable but requiring an effort of will to find compelling.”

Meanwhile, Telegraph writer Jane Shilling said the novel reminded her of Hilary Mantel’s work “Wolf Hall” in that "Signature" also has a “broad historical scope” and has an “ambition refract universal questions about human nature through the experience of a complex individual.”

“Gilbert’s narrative lacks the keen, uncompromising edge of Mantel, and her minor characters are not always conjured with absolute precision,” Shilling wrote. “Nevertheless, this is a big novel in all senses – extensively researched, compellingly readable and with a powerful charm that will surely propel it towards the bestseller lists."